KR20220160491A - Al-based oxidized-layer coating method for reducing hydrogen absorption of hot stamping steel - Google Patents

Al-based oxidized-layer coating method for reducing hydrogen absorption of hot stamping steel Download PDF

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KR20220160491A
KR20220160491A KR1020220061307A KR20220061307A KR20220160491A KR 20220160491 A KR20220160491 A KR 20220160491A KR 1020220061307 A KR1020220061307 A KR 1020220061307A KR 20220061307 A KR20220061307 A KR 20220061307A KR 20220160491 A KR20220160491 A KR 20220160491A
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steel
temperature
oxide layer
hot stamping
present
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이영국
오선근
이준엽
조누리
정현빈
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연세대학교 산학협력단
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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
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    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
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    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/26—After-treatment
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    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
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    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
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    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
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    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
    • C23C2/12—Aluminium or alloys based thereon
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    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
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    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/26—After-treatment
    • C23C2/28—Thermal after-treatment, e.g. treatment in oil bath
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
    • C23C28/30—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
    • C23C28/34—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates
    • C23C28/345—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates with at least one oxide layer
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    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
    • C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
    • C23C8/10—Oxidising
    • C23C8/12—Oxidising using elemental oxygen or ozone
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
    • C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
    • C23C8/10—Oxidising
    • C23C8/16—Oxidising using oxygen-containing compounds, e.g. water, carbon dioxide
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/001—Austenite

Abstract

The present invention relates to an Al-based oxidized-layer coating method for reducing the hydrogen absorption of hot stamping steel, comprising step S1 of annealing steel; step S2 of aluminizing the steel after step S1 is completed; step S3 of forming an oxidized layer by treating the surface of the steel in which step S2 is completed with an oxidizing agent; and step S4 of austenizing the steel after step S3 is completed. The Al-based oxidized-layer coating method according to the present invention can significantly reduce the amount of hydrogen absorbed in steel without additional equipment for lowering a dew point temperature during austenizing of a hot stamping process.

Description

핫스탬핑 강재의 수소흡장저감을 위한 Al계 산화층 도금방법{Al-based oxidized-layer coating method for reducing hydrogen absorption of hot stamping steel}Al-based oxidized-layer coating method for reducing hydrogen absorption of hot stamping steel}

본 발명은 Al계 산화층 도금방법에 관한 것이다. 구체적으로는 핫스탬핑 강재의 수소흡장저감을 위한 Al계 산화층 도금방법에 관한 것이다.The present invention relates to a method for plating an Al-based oxide layer. Specifically, it relates to an Al-based oxide layer plating method for reducing hydrogen storage in hot stamping steel materials.

기존의 핫스템핑 공정에서 오스테나이징(austenitizing) 열처리가 수행되고 있다. 그런데, 오스테나이징 열처리시 열처리 노내의 수증기와 강판의 도금층과의 화학반응을 통하여 수소가 발생하고, 강재 안으로 수소가 흡장되어 수소취성을 일으킨다는 문제가 있다. In the existing hot stamping process, austenitizing heat treatment is performed. However, during austenizing heat treatment, there is a problem that hydrogen is generated through a chemical reaction between water vapor in the heat treatment furnace and the plating layer of the steel sheet, and hydrogen is occluded into the steel material, causing hydrogen embrittlement.

여기서, 수소취성(hydrogen embrittlement)이란 금속재료 특히 철강중에 흡수된 수소에 의하여 강재의 연성과 인성이 저하하고 소성변형 없이도 파괴되는 경향이 증대되는 현상을 말한다. 수소흡수에 의한 파괴를 지연파괴라고도 부르며 이는 주로 결정입계나 응력 집중부위 또는 인장응력이 걸리는 부위에서 주로 일어난다.Here, hydrogen embrittlement refers to a phenomenon in which the ductility and toughness of steel materials are lowered by hydrogen absorbed in metal materials, especially steel materials, and the tendency to fracture without plastic deformation increases. Destruction by hydrogen absorption is also called delayed fracture, and it mainly occurs at grain boundaries, stress concentration regions, or tensile stress regions.

수소취성은 강재가 고강도화가 될수록 더욱 발생이 용이하여 자동차용 고강도강 개발에 큰 장애가 된다. 이를 해결하기 위해서, 추가비용을 지불하면서, 노내의 수증기량 즉, 이슬점 온도를 낮게 하는 장비를 설치하고 있다. Hydrogen embrittlement occurs more easily as the steel material increases in strength, which is a major obstacle to the development of high-strength steel for automobiles. In order to solve this problem, equipment for lowering the amount of water vapor in the furnace, that is, the dew point temperature, is being installed at an additional cost.

(문헌 1) 한국공개특허공보 제10-2017-0056579호(2017.05.23)(Document 1) Korean Patent Publication No. 10-2017-0056579 (May 23, 2017)

본 발명에 따른 핫스탬핑 강재의 수소흡장저감을 위한 Al계 산화층 도금방은 다음과 같은 해결과제를 가진다.The Al-based oxide layer plating room for reducing hydrogen occlusion of hot stamping steel materials according to the present invention has the following problems.

첫째, 핫스템핑 공정의 오스테나이징 열처리 중 이슬점 온도를 낮추는 추가 설비 없이도 강재 내로의 수소 흡장량을 크게 감소시키는 Al계 도금공법을 제시하고자 한다.First, an Al-based plating method that greatly reduces the amount of hydrogen stored in steel without additional equipment for lowering the dew point temperature during the austenizing heat treatment of the hot stamping process is proposed.

둘째, 핫스템핑 공정의 오스테나이징 시 흡수되는 확산성 수소량을 감소시키기 위한 Al계 산화층 도금 시 강재의 온도범위를 구체적으로 제시하고자 한다.Second, the temperature range of the steel when plating the Al-based oxide layer to reduce the amount of diffusible hydrogen absorbed during austenizing in the hot stamping process is presented in detail.

셋째, 평균 연신율 감소량이 최소화되는 Al계 산화층 도금 시 강재의 온도범위를 제시하고자 한다.Third, the temperature range of the steel material when plating the Al-based oxide layer, which minimizes the reduction in average elongation, is presented.

본 발명의 해결과제는 이상에서 언급한 것들에 한정되지 않으며, 언급되지 아니한 다른 해결과제들은 아래의 기재로부터 당업자에게 명확하게 이해될 수 있을 것이다. The problems of the present invention are not limited to those mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

본 발명은 핫스탬핑 강재의 수소흡장저감을 위한 Al계 산화층 도금방법으로서, 강재를 어닐링하는 S1 단계; S1 단계가 완료된 강재를 알루미나이징하는 S2 단계; S2 단계가 완료된 강재 표면에 산화제 처리를 하여 산화층을 형성시키는 S3 단계; 및 상기 S3 단계가 완료된 강재를 오스테나이징하는 S4 단계를 포함한다.The present invention is an Al-based oxide layer plating method for reducing hydrogen occlusion of hot stamping steel, comprising: S1 annealing the steel; Step S2 of aluminizing the steel after step S1 is completed; Step S3 of forming an oxidized layer by treating the surface of the steel material in which step S2 is completed with an oxidizing agent; and a step S4 of austenizing the steel after step S3 has been completed.

본 발명에 있어서, S3 단계의 산화제는 물 또는 산소를 포함할 수 있다.In the present invention, the oxidizing agent of step S3 may include water or oxygen.

본 발명에 있어서, 상기 산화제인 물은 스프레이로 분사되거나, 안개 형태로 분무되어 강재 표면에 공급될 수 있다.In the present invention, the water as the oxidizing agent may be sprayed or sprayed in the form of mist to be supplied to the surface of the steel material.

본 발명에 있어서, S3 단계의 산화층은 MxOy 구조로 구비되며, M은 Al, Cr, Si, Mg 및 Ni 중 하나인 것을 포함할 수 있다.In the present invention, the oxide layer of step S3 has an M x O y structure, and M may include one of Al, Cr, Si, Mg, and Ni.

본 발명에 있어서, S3 단계는 강재의 온도가 25℃~430℃의 온도범위에서 수행될 수 있다.In the present invention, step S3 may be performed in a temperature range of 25 ° C to 430 ° C of the steel material.

본 발명에 있어서, S3 단계는 강재의 온도가 65℃~430℃의 온도범위에서 수행될 수 있다.In the present invention, step S3 may be performed in a temperature range of 65 ℃ ~ 430 ℃ of the steel material.

본 발명에 있어서, S3 단계는 강재의 온도가 65℃~150℃의 온도범위에서 수행될 수 있다.In the present invention, step S3 may be performed in a temperature range of 65 ° C to 150 ° C of the steel material.

본 발명에 있어서, S3 단계는 강재의 온도가 100℃~430℃의 온도범위에서 수행될 수 있다.In the present invention, step S3 may be performed in a temperature range of 100 ℃ ~ 430 ℃ of the steel material.

본 발명에 있어서, S3 단계는 강재의 온도가 100℃~300℃의 온도범위에서 수행될 수 있다.In the present invention, step S3 may be performed in a temperature range of 100 ℃ ~ 300 ℃ of the steel material.

본 발명에 있어서, S3 단계는 S4 단계의 직전까지 수행될 수 있다.In the present invention, step S3 may be performed right before step S4.

본 발명에 따른 핫스탬핑 강재의 수소흡장저감을 위한 Al계 산화층 도금방법은 다음과 같은 효과를 가진다.The Al-based oxide layer plating method for reducing hydrogen occlusion of hot stamping steel materials according to the present invention has the following effects.

첫째, 핫스템핑 공정의 오스테나이징 열처리 중 이슬점 온도를 낮추는 추가 설비 없이도 강재 내로의 수소 흡장량을 크게 감소시키는 효과가 있다.First, there is an effect of greatly reducing the hydrogen storage amount into the steel material without additional equipment for lowering the dew point temperature during the austenizing heat treatment of the hot stamping process.

둘째, 핫스템핑 공정의 오스테나이징 시 흡수되는 확산성 수소량을 감소시키기 위한 Al계 산화층 도금 시 강재의 온도범위를 구체적으로 제시하는 효과가 있다.Second, there is an effect of specifically presenting the temperature range of the steel when plating an Al-based oxide layer to reduce the amount of diffusible hydrogen absorbed during austenizing in the hot stamping process.

셋째, 평균 연신율 감소량이 최소화되는 Al계 산화층 도금 시 강재의 온도범위를 제시하는 효과가 있다.Third, there is an effect of presenting the temperature range of the steel when plating the Al-based oxide layer, which minimizes the decrease in average elongation.

본 발명의 효과는 이상에서 언급된 것들에 한정되지 않으며, 언급되지 아니한 다른 효과들은 아래의 기재로부터 당업자에게 명확하게 이해될 수 있을 것이다.The effects of the present invention are not limited to those mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description below.

도 1은 시간-온도 그래프를 이용하여, 본 발명에 대한 산화제 처리 공정의 개요를 나타낸다.
도 2는 본 발명에 따른 Al계 산화층 도금방법의 기본 개요를 나타내는 모식도이다.
도 3은 산화제 처리 (물 분사)를 하지 않은 Al-Si 도금층의 미세조직 및 화학성분을 나타내는 사진자료이다.
도 4는 시편 온도 25℃에서 산화제 처리(물 분사)를 한 실시예에서의 화학 성분을 나타내는 사진자료이다.
도 5는 시편 온도 65℃에서 산화제 처리(물 분사)를 한 실시예에서의 화학 성분을 나타내는 사진자료이다.
도 6은 시편 온도 100℃에서 산화제 처리(물 분사)를 한 실시예에서의 화학 성분을 나타내는 사진자료이다.
도 7은 시편 온도 200℃에서 산화제 처리(물 분사)를 한 실시예에서의 화학 성분을 나타내는 사진자료이다.
도 8은 시편 온도 300℃에서 산화제 처리(물 분사)를 한 실시예에서의 화학 성분을 나타내는 사진자료이다.
도 9는 시편 온도 400℃에서 산화제 처리(물 분사)를 한 실시예에서의 화학 성분을 나타내는 사진자료이다.
도 10은 도 9의 실시예에서, 불균일한 산화층이 발생되는 것을 나타내는 사진자료이다.
도 11은 산화제 처리 (물 분사)를 할 때, 시편 온도에 따른 산화층 두께 변화를 나타내는 그래프이다.
도 12는 여러 온도(25~430℃)에서 산화제 처리(물 분사)한 시편들을 오스테나이징 열처리(900℃, 2분, 이슬점온도 10℃) 후 시편 내 흡장된 확산성 수소량 변화를 나타내는 그래프이다.
도 13은 여러 온도 구간 (35~55℃, 150℃, 400~550℃)에서 Al과 H2O 반응의 깁스 자유 에너지 변화량(△G)을 나타낸다.
도 14는 여러 온도(25~430℃)에서 산화제 처리(물 분사)한 시편들을 오스테나이징 열처리 (900℃, 2분, 이슬점온도 10℃) 후 측정한 물 분사 시 시편온도에 따른 연신율 감소 변화를 나타낸다.
도 15는 확산성 수소량에 따른 연신율 감소 변화를 나타내는 그래프이다.Figure 1 shows an overview of the oxidizing agent treatment process for the present invention, using a time-temperature graph.
Figure 2 is a schematic diagram showing the basic outline of the Al-based oxide layer plating method according to the present invention.
Figure 3 is a photographic data showing the microstructure and chemical components of the Al-Si plating layer not treated with an oxidizing agent (water spray).
4 is a photographic data showing chemical components in an embodiment in which an oxidizing agent treatment (water spray) was performed at a specimen temperature of 25 ° C.
5 is a photographic data showing chemical components in an embodiment in which an oxidizing agent treatment (water spray) was performed at a specimen temperature of 65 ° C.
6 is a photographic data showing chemical components in an embodiment in which an oxidizing agent treatment (water spray) was performed at a specimen temperature of 100 ° C.
7 is a photographic data showing chemical components in an embodiment in which an oxidizing agent treatment (water spray) was performed at a specimen temperature of 200 ° C.
8 is a photographic data showing chemical components in an embodiment in which an oxidizing agent treatment (water spray) was performed at a specimen temperature of 300 ° C.
9 is a photographic data showing chemical components in an embodiment in which an oxidizing agent treatment (water spray) was performed at a specimen temperature of 400 ° C.
FIG. 10 is a photographic data showing that a non-uniform oxide layer is generated in the embodiment of FIG. 9 .
11 is a graph showing the change in the thickness of the oxide layer according to the temperature of the specimen when oxidizing agent treatment (water spray) is performed.
12 is a graph showing the change in the amount of diffusible hydrogen stored in the specimen after austenizing heat treatment (900 ° C, 2 minutes, dew point temperature 10 ° C) of specimens treated with an oxidizing agent (water spray) at various temperatures (25 to 430 ° C) to be.
Figure 13 shows the Gibbs free energy change (ΔG) of Al and H 2 O reaction in various temperature ranges (35 ~ 55 ℃, 150 ℃, 400 ~ 550 ℃).
14 is a change in elongation reduction according to the specimen temperature when water is sprayed after austenizing heat treatment (900 ° C, 2 minutes, dew point temperature 10 ° C) of specimens treated with an oxidizing agent (water spray) at various temperatures (25 to 430 ° C) indicates
15 is a graph showing the change in elongation reduction according to the amount of diffusible hydrogen.

이하, 첨부한 도면을 참조하여, 본 발명이 속하는 기술분야에서 통상의 지식을 가진 자가 용이하게 실시할 수 있도록 본 발명의 실시예를 설명한다. 본 발명이 속하는 기술분야에서 통상의 지식을 가진 자가 용이하게 이해할 수 있는 바와 같이, 후술하는 실시예는 본 발명의 개념과 범위를 벗어나지 않는 한도 내에서 다양한 형태로 변형될 수 있다. 가능한 한 동일하거나 유사한 부분은 도면에서 동일한 도면부호를 사용하여 나타낸다.Hereinafter, with reference to the accompanying drawings, embodiments of the present invention will be described so that those skilled in the art can easily practice it. As can be easily understood by those skilled in the art to which the present invention pertains, the embodiments described below may be modified in various forms without departing from the concept and scope of the present invention. Where possible, identical or similar parts are indicated using the same reference numerals in the drawings.

본 명세서에서 사용되는 전문용어는 단지 특정 실시예를 언급하기 위한 것이며, 본 발명을 한정하는 것을 의도하지는 않는다. 여기서 사용되는 단수 형태들은 문구들이 이와 명백히 반대의 의미를 나타내지 않는 한 복수 형태들도 포함한다.The terminology used in this specification is only for referring to specific embodiments and is not intended to limit the present invention. As used herein, the singular forms also include the plural forms unless the phrases clearly indicate the opposite.

본 명세서에서 사용되는 "포함하는"의 의미는 특정 특성, 영역, 정수, 단계, 동작, 요소 및/또는 성분을 구체화하며, 다른 특정 특성, 영역, 정수, 단계, 동작, 요소, 성분 및/또는 군의 존재나 부가를 제외시키는 것은 아니다.As used herein, the meaning of "comprising" specifies particular characteristics, regions, integers, steps, operations, elements, and/or components, and other specific characteristics, regions, integers, steps, operations, elements, components, and/or components. It does not exclude the presence or addition of groups.

본 명세서에서 사용되는 기술용어 및 과학용어를 포함하는 모든 용어들은 본 발명이 속하는 기술분야에서 통상의 지식을 가진 자가 일반적으로 이해하는 의미와 동일한 의미를 가진다. 사전에 정의된 용어들은 관련기술문헌과 현재 개시된 내용에 부합하는 의미를 가지는 것으로 추가 해석되고, 정의되지 않는 한 이상적이거나 매우 공식적인 의미로 해석되지 않는다.All terms including technical terms and scientific terms used in this specification have the same meaning as commonly understood by a person of ordinary skill in the art to which the present invention belongs. The terms defined in the dictionary are additionally interpreted as having a meaning consistent with the related technical literature and the currently disclosed content, and are not interpreted in an ideal or very formal meaning unless defined.

이하에서는 도면을 참고하여 본 발명을 설명하고자 한다. 참고로, 도면은 본 발명의 특징을 설명하기 위하여, 일부 과장되게 표현될 수도 있다. 이 경우, 본 명세서의 전 취지에 비추어 해석되는 것이 바람직하다.Hereinafter, the present invention will be described with reference to the drawings. For reference, the drawings may be partially exaggerated in order to explain the features of the present invention. In this case, it is preferable to interpret in light of the whole purpose of this specification.

본 발명에 따른 Al계 산화층 도금공법은 도금욕에서 꺼낸 후 핫스템핑 공정의 오스테나이징 직전까지 도금층 표면을 산화시킬 수 있는 산화제를 사용하여 최표면에 얇은 산화층을 형성시키는 방법에 관한 것이다. 본 발명을 통해 오스테나이징 열처리 중 이슬점 온도를 낮추는 추가 설비 없이도 강재 내로의 수소 흡장량을 크게 줄이는 것이 가능하다.The Al-based oxide layer plating method according to the present invention relates to a method of forming a thin oxide layer on the outermost surface by using an oxidizing agent capable of oxidizing the surface of the plating layer until immediately before austenizing in the hot stamping process after removal from the plating bath. Through the present invention, it is possible to greatly reduce the amount of hydrogen absorbed into the steel material without additional equipment for lowering the dew point temperature during the austenizing heat treatment.

본 발명은 핫스탬핑 강재의 수소흡장저감을 위한 Al계 산화층 도금방법으로서, 강재를 어닐링하는 S1 단계; S1 단계가 완료된 강재를 알루미나이징하는 S2 단계; S2 단계가 완료된 강재 표면에 산화제 처리를 하는 S3 단계; 및 상기 S3 단계가 완료된 강재를 오스테나이징하는 S4 단계를 포함한다(도 1 참조).The present invention is an Al-based oxide layer plating method for reducing hydrogen occlusion of hot stamping steel, comprising: S1 annealing the steel; Step S2 of aluminizing the steel after step S1 is completed; Step S3 of oxidizing agent treatment on the steel surface after step S2 is completed; And a step S4 of austenizing the steel after step S3 has been completed (see FIG. 1).

본 발명에 따른 S3 단계의 산화제는 물 또는 산소를 포함할 수 있다.The oxidizing agent of step S3 according to the present invention may include water or oxygen.

본 발명에 따른 산화제가 물인 경우, 스프레이로 분사되거나, 안개 형태로 분무되어 강재 표면에 공급될 수 있다. 물은 기 설정된 온도에서 기 설정된 시간동안 분사될 수 있다. 본 발명에서는 물의 온도보다 강재의 온도가 물성변화의 주된 요소에 해당되므로, 물의 기 설정 온도는 다양하게 적용가능할 것이다.When the oxidizing agent according to the present invention is water, it may be sprayed or sprayed in the form of mist and supplied to the steel surface. Water may be sprayed at a preset temperature for a preset time. In the present invention, since the temperature of the steel material corresponds to the main factor in changing the physical properties rather than the temperature of the water, the preset temperature of the water will be variously applicable.

본 발명에 따른 산화제가 산소 가스인 경우, 고압 기체 상태로 노즐을 이용하여 분사될 수 있다.When the oxidizing agent according to the present invention is oxygen gas, it can be injected using a nozzle in a high-pressure gas state.

도 1은 시간-온도 그래프를 이용하여, 본 발명에 대한 산화제 처리 공정의 개요를 나타낸다. 도 2는 본 발명에 따른 Al계 산화층 도금방법의 기본 개요를 나타내는 모식도이다.Figure 1 shows an overview of the oxidizing agent treatment process for the present invention, using a time-temperature graph. Figure 2 is a schematic diagram showing the basic outline of the Al-based oxide layer plating method according to the present invention.

오스테나이징 공정 중 고온에서 2Al (l) + 3H2O (g) → Al2O3 (s) + 6H 화학 반응을 통해 도금층의 표면에 Al2O3가 생성됨과 동시에 수소(H) 또한 생성된다. 이때 생성된 H는 도금층을 통해 모재 내부로 흡장되게 된다. 2Al (l) + 3H 2 O (g) → Al 2 O 3 (s) + 6H At high temperature during the austenizing process, Al 2 O 3 is generated on the surface of the plating layer through a chemical reaction and hydrogen (H) is also generated. do. At this time, the generated H is occluded into the base material through the plating layer.

따라서, S2 단계에 해당되는 도금욕에서 꺼낸 이후, S4 단계에 해당되는 핫스템핑 공정의 오스테나이징 직전 까지 도금층 표면을 산화시킬 수 있는 산화제를 사용하여 최표면에 얇은 산화층을 형성시킬 수 있다.Therefore, a thin oxide layer may be formed on the outermost surface by using an oxidizing agent capable of oxidizing the surface of the plating layer until immediately before austenizing in the hot stamping process corresponding to step S4 after being taken out of the plating bath corresponding to step S2.

S3 단계의 산화층은 MxOy 구조로 구비되며, M은 Al, Cr, Si, Mg, 및 Ni 중 어느 하나인 것을 포함한다. 다만, 이에 국한되지 않고 다양한 물질의 산화층이 형성될 수 있다.The oxide layer of step S3 has an M x O y structure, and M includes any one of Al, Cr, Si, Mg, and Ni. However, it is not limited thereto, and oxide layers of various materials may be formed.

이와 같이 강재 표면에 형성된 산화층은 도금층의 Al과 H2O의 접촉을 막음으로써, 전술한 화학 반응을 억제시켜 수소의 흡장을 감소시킬 수 있다.As such, the oxide layer formed on the surface of the steel material prevents contact between Al and H 2 O of the plating layer, thereby suppressing the above-described chemical reaction and reducing hydrogen occlusion.

본 발명에 따른 S3 단계는 S4 단계의 직전까지 수행될 수 있다.Step S3 according to the present invention may be performed right before step S4.

여기서, 'S4 단계의 직전'은 S4 단계에 해당되는 오스테나이징 단계의 온도의 직전 온도까지를 의미한다.Here, 'just before step S4' means up to the temperature right before the temperature of the austenizing step corresponding to step S4.

도 3은 산화제 처리(물 분사)를 하지 않은 Al-Si 도금층의 미세조직 및 화학성분을 나타내는 사진자료이다.Figure 3 is a photographic data showing the microstructure and chemical components of the Al-Si plating layer not treated with an oxidizing agent (water spray).

SEM 이미지를 통해 Al-Si 도금층의 상분석과 EDXS mapping을 통해 도금층 최표면부의 산화층을 분석하였다. 분석 결과, 모재는 페라이트(ferrite)와 펄라이트(pearlite)로 구성되며, 그 위에 Al-Si 도금층이 존재한다. Al-Si 도금층의 두께는 ~30μm 이며, 대부분 Al에 Si이 고용되어있는 상으로 구성되어 있다. 또한 Al-Si 도금층의 내부 및 직하에 Fe2SiAl7가 존재하며, Fe2SiAl7 층과 모재 사이에는 Fe2Al3, FeAl3가 얇은 층으로 존재한다. 도금층의 최표면부에는 ~0.52μm의 산화물층이 형성되어 있었다.The phase analysis of the Al-Si plating layer through SEM images and the oxide layer on the outermost surface of the plating layer were analyzed through EDXS mapping. As a result of the analysis, the base material is composed of ferrite and pearlite, and an Al-Si plating layer exists thereon. The thickness of the Al-Si plating layer is ~30μm, and most of it is composed of a phase in which Si is dissolved in Al. In addition, Fe 2 SiAl 7 exists inside and directly below the Al-Si plating layer, and Fe 2 Al 3 and FeAl 3 exist as thin layers between the Fe 2 SiAl 7 layer and the base material. An oxide layer of ~0.52 μm was formed on the outermost part of the plating layer.

본 발명에 따른 S3 단계는 강재의 온도가 25℃~430℃인 온도범위에서 수행될 수 있다.Step S3 according to the present invention may be performed in a temperature range of 25 ° C to 430 ° C of the steel material.

강재의 온도가 25℃ 미만이면, 산화제와 도금재가 반응하여 균일하고 치밀한 산화층이 형성될 충분한 온도가 되지 못하는 문제점이 있다. 또한, 강재의 온도가 430℃를 초과하면 강재 표면에 생성되는 산화층의 두께가 균일하지 못하고, 산화층이 형성이 되더라도 냉각 중 균열 생성 때문에 수소의 흡장을 저하시키는 능력이 감소한다는 문제점이 있다.If the temperature of the steel material is less than 25° C., there is a problem in that the temperature is not sufficient to form a uniform and dense oxide layer by reacting the oxidizing agent and the plating material. In addition, when the temperature of the steel material exceeds 430 ℃, the thickness of the oxide layer generated on the surface of the steel material is not uniform, and even if the oxide layer is formed, there is a problem that the ability to reduce hydrogen absorption is reduced due to crack formation during cooling.

본 발명에 따른 S3 단계는 강재의 온도가 65℃~430℃의 온도범위에서 수행될 수 있다. 강재의 온도 범위가 65℃~430℃인 경우, 표 1과 같이 평균 확산성 수소량(maaa ppm)은 0.16~0.27로서 0.27 이하의 값을 가질 수 있다.Step S3 according to the present invention may be performed in a temperature range of 65 ° C to 430 ° C of the steel material. When the temperature range of the steel is 65 ℃ ~ 430 ℃, as shown in Table 1, the average diffusible hydrogen amount (maaa ppm) may have a value of 0.27 or less as 0.16 ~ 0.27.

본 발명에 따른 S3 단계는 강재의 온도가 65℃~150℃의 온도범위에서 수행될 수 있다. 강재의 온도 범위가 65℃~150℃인 경우, 표 1과 같이 평균 확산성 수소량(maaa ppm)은 0.16~0.20로서 0.20 이하의 값을 가질 수 있다.Step S3 according to the present invention may be performed in a temperature range of 65 ° C to 150 ° C of the steel material. When the temperature range of the steel is 65 ℃ ~ 150 ℃, as shown in Table 1, the average diffusible hydrogen amount (maaa ppm) may have a value of 0.20 or less as 0.16 ~ 0.20.

본 발명에 따른 S3 단계는 강재의 온도가 100℃~430℃의 온도범위에서 수행될 수 있다. 강재의 온도 범위가 100℃~430℃인 경우, 표 1과 같이 평균 확산성 수소량(maaa ppm)은 0.12~0.27로서 최저값 0.12를 포함하며 0.27 이하의 값을 가질 수 있다.Step S3 according to the present invention may be performed in a temperature range of 100 ° C to 430 ° C of the steel material. When the temperature range of the steel is 100 ° C to 430 ° C, as shown in Table 1, the average diffusible hydrogen amount (maaa ppm) is 0.12 to 0.27, including the lowest value of 0.12 and may have a value of 0.27 or less.

본 발명에 따른 S3 단계는 강재의 온도가 100℃~300℃의 온도범위에서 수행될 수 있다. 강재의 온도 범위가 100℃~300℃인 경우, 표 1과 같이 평균 확산성 수소량(maaa ppm)은 0.12~0.22의 값을 가지며, 또한 표 2와 같이, 평균 연신율 감소량(%)이 30% 미만의 값을 가질 수 있다.Step S3 according to the present invention may be performed in a temperature range of 100 ° C to 300 ° C of the steel material. When the temperature range of the steel is 100 ℃ ~ 300 ℃, as shown in Table 1, the average diffusible hydrogen amount (maaa ppm) has a value of 0.12 ~ 0.22, and as shown in Table 2, the average elongation reduction (%) is 30% may have a value less than

이하에서는, S3 단계에서 강재 시편의 여러 온도 별로 산화제 처리(물 분사)를 한 실시예에 관한 도면 및 그래프 등의 자료를 통해, 본 발명을 설명하고자 한다.Hereinafter, the present invention will be described through data such as drawings and graphs related to an embodiment in which an oxidizing agent treatment (water spray) is performed for each temperature of a steel specimen in step S3.

본 실시예들의 경우, 본 발명이 적용가능한 자동차용 강판과 유사한 두께에 해당되는 약 1.5mm 두께를 가진 직육면체 형상의 강재 시편이 사용되었다. In the case of the present embodiments, a rectangular parallelepiped-shaped steel specimen having a thickness of about 1.5 mm corresponding to a thickness similar to that of a steel sheet for automobiles to which the present invention is applicable was used.

본 명세서에서 강재 시편의 온도는 산화층이 형성되는 강재의 표면온도가 기준이 될 수 있다. 다만, 두께가 얇기 때문에, 강재의 표면온도와 중심온도의 편차가 크지 않기 때문에, 실무적으로는 혼용되어 사용되는 경우도 있을수 있다.In the present specification, the temperature of the steel specimen may be based on the surface temperature of the steel material in which the oxide layer is formed. However, since the thickness is thin, the deviation between the surface temperature and the center temperature of the steel material is not large, so in practice, there may be cases where they are used together.

강재 시편 온도는 열전대(TC:Thermo Couple)와 멀티미터(multimeter)를 통해 측정되었다. 측정방법으로는 열전대(TC)를 시편 표면에 점용접으로 부착을 하거나, 시편의 RD(Rolling Direction) 면에 구멍을 만들어 열전대(TC)를 삽입하여 측정하였다. The temperature of the steel specimen was measured through a thermocouple (TC: Thermo Couple) and a multimeter. As a measurement method, a thermocouple (TC) was attached to the surface of the specimen by spot welding, or a hole was made in the RD (Rolling Direction) surface of the specimen and the thermocouple (TC) was inserted.

도 4는 시편 온도 25℃에서 산화제 처리(물 분사)를 한 실시예에서의 화학 성분을 나타내는 사진자료이다. 시편 온도가 25℃일 때 ~0.57μm의 산화층이 형성되었는데, 이는 물 분사를 하지 않은 경우에 비해, 산화층이 다소 증가되었음을 알 수 있다. 4 is a photographic data showing chemical components in an embodiment in which an oxidizing agent treatment (water spray) was performed at a specimen temperature of 25 ° C. When the sample temperature was 25 °C, an oxide layer of ~0.57 μm was formed, indicating that the oxide layer was slightly increased compared to the case where water spray was not applied.

도 5는 시편 온도 65℃에서 산화제 처리(물 분사)를 한 실시예에서의 화학 성분을 나타내는 사진자료이다. 도 6은 시편 온도 100℃에서 산화제 처리(물 분사)를 한 실시예에서의 화학 성분을 나타내는 사진자료이다. 도 7은 시편 온도 200℃에서 산화제 처리(물 분사)를 한 실시예에서의 화학 성분을 나타내는 사진자료이다. 도 8은 시편 온도 300℃에서 산화제 처리(물 분사)를 한 실시예에서의 화학 성분을 나타내는 사진자료이다. 도 9는 시편 온도 400℃에서 산화제 처리(물 분사)를 한 실시예에서의 화학 성분을 나타내는 사진자료이다. 도 10은 도 9의 실시예에서, 불균일한 산화층이 발생되는 것을 나타내는 사진자료이다.5 is a photographic data showing chemical components in an embodiment in which an oxidizing agent treatment (water spray) was performed at a specimen temperature of 65 ° C. 6 is a photographic data showing chemical components in an embodiment in which an oxidizing agent treatment (water spray) was performed at a specimen temperature of 100 ° C. 7 is a photographic data showing chemical components in an embodiment in which an oxidizing agent treatment (water spray) was performed at a specimen temperature of 200 ° C. 8 is a photographic data showing chemical components in an embodiment in which an oxidizing agent treatment (water spray) was performed at a specimen temperature of 300 ° C. 9 is a photographic data showing chemical components in an embodiment in which an oxidizing agent treatment (water spray) was performed at a specimen temperature of 400 ° C. 10 is a photographic data showing that a non-uniform oxide layer is generated in the embodiment of FIG. 9 .

도 11은 산화제 처리(물 분사)를 할 때, 시편 온도에 따른 산화층 두께 변화를 나타내는 그래프이다. 도 4 내지 도 10의 실시예를 보면, 강재 시편 온도가 높아질수록 산화층의 두께가 점차 증가하는 경향을 확인할 수 있다. 11 is a graph showing the change in the thickness of the oxide layer according to the temperature of the specimen when oxidizing agent treatment (water spray) is performed. 4 to 10, it can be seen that the thickness of the oxide layer gradually increases as the temperature of the steel specimen increases.

강재 시편 온도가 400℃인 경우, 도 9와 같이 ~1.8μm 까지 증가하였고, 도 10과 같이 ~3.9μm 두께의 산화층도 형성이 되었다. 이와 같이, 시편 온도가 높아질수록 산화층 두께 편차가 커지는 것으로 보아, 온도가 높아질수록 산화층이 불균일하게 형성되거나, 형성 후 냉각 중에 깨지는 것으로 판단된다.When the steel specimen temperature was 400° C., the temperature increased to ~1.8 μm as shown in FIG. 9, and an oxide layer having a thickness of ~3.9 μm was also formed as shown in FIG. 10. As such, as the temperature of the specimen increases, the thickness variation of the oxide layer increases, and as the temperature increases, the oxide layer is non-uniformly formed or cracked during cooling after formation.

도 12는 여러 온도(25~430 ℃)에서 산화제 처리(물 분사)한 시편들을 오스테나이징 열처리(900℃, 2분, 이슬점온도 10℃) 후 시편 내 흡장된 확산성 수소량 변화를 나타내는 그래프이다. 12 is a graph showing the change in the amount of diffusible hydrogen occluded in the specimen after austenizing heat treatment (900 ° C, 2 minutes, dew point temperature 10 ° C) of specimens treated with an oxidizing agent (water spray) at various temperatures (25 to 430 ° C) to be.

아래 표 1은 시편 강재 온도 별로 평균 확산성 수소량을 표시한 것이다.Table 1 below shows the average amount of diffusible hydrogen for each sample steel temperature.

Figure pat00001
Figure pat00001

확산성 수소는 관상로를 이용하여 시편을 200℃/h의 승온속도로 300℃ 까지 승온 시키며, 승온 과정에서 빠져나오는 수소를 열탈착분석법(TDA: Thermal desorption analysis)으로 측정하였다. 모든 시편들이 물 분사하지 않은 시편의 수소량(0.44 mass ppm) 보다 더 적은 수소량을 갖는다는 것을 알 수 있다. 특히, 물 분사 시 시편 온도가 100℃ 일 때, 오스테나이징 후 수소 흡장량이 가장 적고, 그 보다 온도가 낮거나 높으면 다시 수소 흡장량이 증가하였다. For diffusive hydrogen, the specimen was heated up to 300 °C at a heating rate of 200 °C/h using a tubular furnace, and the hydrogen escaping during the heating process was measured by thermal desorption analysis (TDA). It can be seen that all the samples have less hydrogen content than that of the sample without water spray (0.44 mass ppm). In particular, when the sample temperature was 100 ° C during water spray, the hydrogen occlusion amount after austenizing was the lowest, and when the temperature was lower or higher than that, the hydrogen occlusion amount increased again.

이는, 물을 분사하더라도 강재 시편의 온도가 100℃ 보다 낮으면 산화층이 매우 적게 생기기 때문이다. 또한, 100℃ 보다 온도가 높으면 산화층이 더 두껍게 생기기는 하지만, 매우 불균일하고 산화층 내 균열 등이 생겨서 외부 수분의 침투를 막아주는 효과가 감소하기 때문으로 판단된다.This is because, even if water is sprayed, an oxide layer is formed very little when the temperature of the steel specimen is lower than 100 ° C. In addition, if the temperature is higher than 100 ° C., the oxide layer becomes thicker, but it is very non-uniform and cracks occur in the oxide layer, which is considered to be because the effect of preventing the penetration of external moisture is reduced.

도 13은 여러 온도 구간 (35~55℃, 150℃, 400~550℃)에서 Al과 H2O 반응의 깁스 자유 에너지 변화량(△G)을 나타낸다. Figure 13 shows the change in Gibbs free energy (ΔG) of Al and H 2 O reaction in various temperature ranges (35 ~ 55 ℃, 150 ℃, 400 ~ 550 ℃).

△G 값은 열역학적 전산 해석 시뮬레이션 프로그램인 Factsage를 사용하여 계산하였다. 이론적으로 △G<0 인 경우 정반응이 자발적이고, 더 큰 음의 값을 가지는 반응이 우세하다. 따라서, △G값을 통해 여러 온도 구간(예를 들어 35~55℃, 400~550℃ 등)에서 산화층이 얼마나 자발적으로 생성될 수 있는지 확인할 수 있다. ΔG values were calculated using Factsage, a thermodynamic computational analysis simulation program. Theoretically, when ΔG<0, the forward reaction is spontaneous, and the reaction with a larger negative value is dominant. Therefore, it is possible to check how spontaneously an oxide layer can be generated in various temperature ranges (eg, 35 to 55° C., 400 to 550° C., etc.) through the ΔG value.

본 발명에 따른 실시예의 경우, 550℃까지 가열된 강재 시편을 산화제 처리(물 분사) 장치까지 이동시키는 과정에서 발생되는 시편 온도 저하로 인해 430℃를 초과하는 온도는 측정이 곤란하였다. In the case of the embodiment according to the present invention, it was difficult to measure a temperature exceeding 430 ° C due to the decrease in the specimen temperature occurring in the process of moving the steel specimen heated to 550 ° C to the oxidizing agent treatment (water spray) device.

따라서 Factsage를 사용하여 △G값을 계산하고, 이를 직접 실험한 온도대와 비교하였다. 계산 결과, 450~550℃ 구간과 400℃의 △G값의 차이는 미미하였고, 이를 통해 450~550℃ 구간에서도 강재 시편 온도 400℃에서 산화제 처리(물 분사)를 한 것과 유사한 산화층 두께 및 형상, 그리고 수소 흡장량을 나타낼 것으로 판단된다. Therefore, the ΔG value was calculated using Factsage and compared with the temperature range directly tested. As a result of the calculation, the difference between the ΔG value between 450~550℃ and 400℃ was insignificant. Through this, even in the 450~550℃ section, the thickness and shape of the oxide layer similar to that of the oxidizing agent treatment (water spray) at 400℃ of the steel specimen, And it is determined that it represents the hydrogen occlusion amount.

또한, 35~55℃ 구간은 150℃와 유사하고 400℃보다 낮은 △G값을 나타낸다. 따라서, 35~55℃ 구간에서의 수소 흡장량은 시편온도 150℃와 400℃ 사이의 수소 흡장량 값을 가질 것으로 판단된다. In addition, the 35 to 55 ° C section shows a ΔG value similar to 150 ° C and lower than 400 ° C. Therefore, it is determined that the hydrogen occlusion in the range of 35 to 55 ° C will have a hydrogen occlusion value between the specimen temperature of 150 ° C and 400 ° C.

도 14는 여러 온도(25~430℃)에서 산화제 처리(물 분사)한 시편들을 오스테나이징 열처리 (900℃, 2분, 이슬점온도 10℃) 후 측정한 물 분사 시 시편온도에 따른 연신율 감소 변화를 나타낸다. 14 is a change in elongation reduction according to the specimen temperature when water is sprayed after austenizing heat treatment (900 ° C, 2 minutes, dew point temperature 10 ° C) of specimens treated with an oxidizing agent (water spray) at various temperatures (25 to 430 ° C) indicates

아래 표 2는 강재 시편 온도 별로 평균 연신율 감소량을 표시한 것이다.Table 2 below shows the average reduction in elongation for each steel specimen temperature.

Figure pat00002
Figure pat00002

강재 시편 온도 25℃, 400℃, 430℃의 경우에는 물 분사하지 않은 시편의 연신율 감소(38.4%)와 유사하였다. 그러나, 그 이외의 온도들에서는 연신율 감소가 줄어들었다. 특히, 시편 온도가 100℃ 일 때 연신율 감소가 가장 적었다.In the case of steel specimen temperatures of 25℃, 400℃, and 430℃, the reduction in elongation (38.4%) of the specimen without water spray was similar. However, at other temperatures the elongation reduction was reduced. In particular, the reduction in elongation was the least when the specimen temperature was 100 °C.

도 15는 확산성 수소량에 따른 연신율 감소 변화를 나타내는 그래프이다.15 is a graph showing the change in elongation reduction according to the amount of diffusible hydrogen.

25℃, 400℃, 430℃를 제외한 모든 조건에서 물 분사하지 않은 시편보다 수소량과 연신율 감소가 줄어든 것을 확인할 수 있었다. 또한, 오스테나이트 중 흡장된 수소함량이 증가함에 따라 연신율 감소가 증가하는 것을 알 수 있었다. 시편 온도 100℃에서 물 분사한 시편이 오스테나이징 후 가장 적은 수소를 함유하여 가장 낮은 연신율 감소를 보여서 수소 취성에 대한 저항성이 가장 우수한 것으로 나타났다.In all conditions except 25 ℃, 400 ℃, 430 ℃, it was confirmed that the hydrogen content and elongation decrease were reduced compared to the specimens without water spray. In addition, it was found that the decrease in elongation increased as the hydrogen content stored in austenite increased. The specimen sprayed with water at a specimen temperature of 100 °C contained the least hydrogen after austenizing and showed the lowest reduction in elongation, indicating the best resistance to hydrogen embrittlement.

본 명세서에서 설명되는 실시예와 첨부된 도면은 본 발명에 포함되는 기술적 사상의 일부를 예시적으로 설명하는 것에 불과하다. 따라서, 본 명세서에 개시된 실시예들은 본 발명의 기술적 사상을 한정하기 위한 것이 아니라 설명하기 위한 것이므로, 이러한 실시예에 의하여 본 발명의 기술 사상의 범위가 한정되는 것은 아님은 자명하다. 본 발명의 명세서 및 도면에 포함된 기술적 사상의 범위 내에서 당업자가 용이하게 유추할 수 있는 변형 예와 구체적인 실시 예는 모두 본 발명의 권리범위에 포함되는 것으로 해석되어야 할 것이다.The embodiments described in this specification and the accompanying drawings merely illustrate some of the technical ideas included in the present invention by way of example. Therefore, since the embodiments disclosed in this specification are intended to explain rather than limit the technical spirit of the present invention, it is obvious that the scope of the technical spirit of the present invention is not limited by these embodiments. All modified examples and specific examples that can be easily inferred by those skilled in the art within the scope of the technical idea included in the specification and drawings of the present invention should be construed as being included in the scope of the present invention.

Claims (10)

강재를 어닐링하는 S1 단계;
S1 단계가 완료된 강재를 알루미나이징하는 S2 단계;
S2 단계가 완료된 강재 표면에 산화제 처리를 하여 산화층을 형성시키는 S3 단계; 및
상기 S3 단계가 완료된 강재를 오스테나이징하는 S4 단계를 포함하는 것을 특징으로 하는 핫스탬핑 강재의 수소흡장저감을 위한 Al계 산화층 도금방법.S1 step of annealing the steel;
Step S2 of aluminizing the steel after step S1 is completed;
Step S3 of forming an oxidized layer by treating the surface of the steel material in which step S2 is completed with an oxidizing agent; and
An Al-based oxide layer plating method for reducing hydrogen occlusion of hot stamping steel, characterized in that it comprises a step S4 of austenizing the steel after the step S3 has been completed. 청구항 1에 있어서,
S3 단계의 산화제는 물 또는 산소를 포함하는 것을 특징으로 하는 핫스탬핑 강재의 수소흡장저감을 위한 Al계 산화층 도금방법.The method of claim 1,
The Al-based oxide layer plating method for reducing hydrogen absorption of hot stamping steel, characterized in that the oxidizing agent in step S3 contains water or oxygen. 청구항 2에 있어서,
상기 산화제인 물은 스프레이로 분사되거나, 안개 형태로 분무되어 강재 표면에 공급되는 것을 특징으로 하는 핫스탬핑 강재의 수소흡장저감을 위한 Al계 산화층 도금방법.The method of claim 2,
The Al-based oxide layer plating method for reducing hydrogen absorption of hot stamping steel, characterized in that the water as the oxidizing agent is sprayed or sprayed in the form of mist and supplied to the steel surface. 청구항 1에 있어서,
S3 단계의 산화층은 MxOy 구조로 구비되며,
M은 Al, Cr, Si, Mg 및 Ni 중 어느 하나인 것을 포함하는 것을 특징으로 하는 핫스탬핑 강재의 수소흡장저감을 위한 Al계 산화층 도금방법.The method of claim 1,
The oxide layer of step S3 has an M x O y structure,
M is an Al-based oxide layer plating method for reducing hydrogen occlusion of hot stamping steel, characterized in that it comprises any one of Al, Cr, Si, Mg and Ni. 청구항 1에 있어서,
S3 단계는 강재의 온도가 25℃~430℃의 온도범위에서 수행되는 것을 특징으로 하는 핫스탬핑 강재의 수소흡장저감을 위한 Al계 산화층 도금방법.The method of claim 1,
Step S3 is an Al-based oxide layer plating method for reducing hydrogen occlusion of hot stamping steel, characterized in that the temperature of the steel is carried out in the temperature range of 25 ℃ ~ 430 ℃. 청구항 5에 있어서,
S3 단계는 강재의 온도가 65℃~430℃의 온도범위에서 수행되는 것을 특징으로 하는 핫스탬핑 강재의 수소흡장저감을 위한 Al계 산화층 도금방법.The method of claim 5,
Step S3 is an Al-based oxide layer plating method for reducing hydrogen occlusion of hot stamping steel, characterized in that the temperature of the steel is carried out in the temperature range of 65 ℃ ~ 430 ℃. 청구항 5에 있어서,
S3 단계는 강재의 온도가 65℃~150℃의 온도범위에서 수행되는 것을 특징으로 하는 핫스탬핑 강재의 수소흡장저감을 위한 Al계 산화층 도금방법.The method of claim 5,
Step S3 is an Al-based oxide layer plating method for reducing hydrogen occlusion of hot stamping steel, characterized in that the temperature of the steel is carried out in the temperature range of 65 ℃ ~ 150 ℃. 청구항 5에 있어서,
S3 단계는 강재의 온도가 100℃~430℃의 온도범위에서 수행되는 것을 특징으로 하는 핫스탬핑 강재의 수소흡장저감을 위한 Al계 산화층 도금방법.The method of claim 5,
Step S3 is an Al-based oxide layer plating method for reducing hydrogen occlusion of hot stamping steel, characterized in that the temperature of the steel is carried out in the temperature range of 100 ℃ ~ 430 ℃. 청구항 5에 있어서,
S3 단계는 강재의 온도가 100℃~300℃의 온도범위에서 수행되는 것을 특징으로 하는 핫스탬핑 강재의 수소흡장저감을 위한 Al계 산화층 도금방법.The method of claim 5,
Step S3 is an Al-based oxide layer plating method for reducing hydrogen occlusion of hot stamping steel, characterized in that the temperature of the steel is carried out in the temperature range of 100 ℃ ~ 300 ℃. 청구항 1에 있어서,
S3 단계는 S4 단계의 직전까지 수행되는 것을 특징으로 하는 핫스탬핑 강재의 수소흡장저감을 위한 Al계 산화층 도금방법.
The method of claim 1,
Step S3 is an Al-based oxide layer plating method for reducing hydrogen occlusion of hot stamping steel, characterized in that it is performed immediately before step S4.
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20170056579A (en) 2014-09-16 2017-05-23 도레이 카부시키가이샤 Metal composite carbon material, fuel cell catalyst, fuel cell, hydrogen-occluding material, hydrogen tank, and production method for metal composite carbon material

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